BSCI—3：配置EIGRP-MD5认证

R2 查看EIGRP邻居表：

r2#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

H   Address          Interface     Hold Uptime    SRTT   RTO   Q  Seq  Type

                                            (sec)     (ms)          Cnt Num

0   192.168.1.1       Et0/0         10   00:02:28    3    200   0    2 

r2#

步骤二：两边启用MD5认证，但是KEY-ID不一样，邻居是否能建立，为什么?  （注：故障）

R1:

r1#

r1#conf t

r1(config)#key chain eigrp       //定义钥匙链eigrp（名字任意取）

r1(config-keychain)#key 1       //KEY ID为1

r1(config-keychain-key)#key-string cisco     //密码为cisco

r1(config-keychain-key)#exit

r1(config-keychain)#exit

r1(config)#interface e0/0

r1(config-if)#ip authentication key-chain eigrp 1 eigrp    //启用EIGRP认证

r1(config-if)#ip authentication mode eigrp 1 md5      //认证模式MD5

r1(config-if)#end

r1#

R2:

r2#

r2#conf t

r2(config)#key chain eigrp

r2(config-keychain)#key 2       //KEY ID为2

r2(config-keychain-key)#key-string cisco

r2(config-keychain-key)#exit

r2(config-keychain)#exit

r2(config)#interface e0/0

r2(config-if)#ip authentication key-chain eigrp 1 eigrp

r2(config-if)#ip authentication mode eigrp 1 md5

r2(config-if)#end

r2#

查看邻居表：

r2#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

r2#

//说明没有建立邻居关系，为什么？

查看Debug:

r2#debug eigrp packets

EIGRP Packets debugging is on

(UPDATE, REQUEST, QUERY, REPLY, HELLO, IPXSAP, PROBE, ACK, STUB, SIAQUERY, SIAREPLY)

*Mar  1 22:31:40.962: EIGRP: Sending HELLO on Ethernet0/0

*Mar  1 22:31:40.962:   AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0

*Mar  1 22:31:41.187: EIGRP: pkt authentication key id = 1, key not defined or not live

//这里清楚的看到，收到的KEY ID = 1 ，key没有定义或不存在,因为们的KEY ID为2

*Mar  1 22:31:41.187: EIGRP: Ethernet0/0: ignored packet from 192.168.1.1, opcode = 5 (invalid authentication)  

步骤三：双方KEY ID一致，但密码不一致，邻居关系是否能建立，为什么？ （注：故障）

R2:

r2#

r2#conf t

r2(config)#key chain eigrp

r2(config-keychain)#key 1

r2(config-keychain-key)#key-string cisco1     //这里密码是cisco1，与r1不一致

r2(config-keychain-key)#end

r2#

查看邻居表：

r2#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

r2#

//还是一样没有建立，为什么？

查看Debug:

r2#debug eigrp packets

EIGRP Packets debugging is on

    (UPDATE, REQUEST, QUERY, REPLY, HELLO, IPXSAP, PROBE, ACK, STUB, SIAQUERY, SIAREPLY)

r2#

*Mar  1 22:46:14.094: EIGRP: pkt key id = 1, authentication mismatch

//这里没有显示KEY ID不正确，而是认证不匹配，说明密码不一致.

*Mar  1 22:46:14.094: EIGRP: Ethernet0/0: ignored packet from 192.168.1.1, opcode = 5 (invalid authentication)

 步骤四：双方KEY ID一样，密码也一样,可以正常建立邻居关系.

R1：

r1(config)#

r1(config)#key chain eigrp

r1(config-keychain)#key 1

r1(config-keychain-key)#key-string cisco

r1(config)#interface e0/0

r1(config-if)#ip authentication key-chain eigrp 1 eigrp

r1(config-if)#ip authentication mode eigrp 1 md5

r1(config-keychain-key)#end

r2#

R2:

r2(config)#

r2(config)#key chain eigrp

r2(config-keychain)#key 1              

r2(config-keychain-key)# key-string cisco  

r2(config)#interface e0/0

r2(config-if)#ip authentication key-chain eigrp 1 eigrp

r2(config-if)#ip authentication mode eigrp 1 md5

*Mar  1 22:51:33.037: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.1.1 (Ethernet0/0) is up: new adjacency        //正常建立，OK！！

r2(config-keychain-key)#end

r2#

步骤五：分别在R1与R2上验证

R1:

查看邻居表：

r1#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq Type

                                            (sec)         (ms)       Cnt Num

0   192.168.1.2             Et0/0             13 00:03:00 1321  5000  0  9  

r1#

查看路由表：

r1#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

Gateway of last resort is not set

     1.0.0.0/24 is subnetted, 1 subnets

C       1.1.1.0 is directly connected, Loopback0

     2.0.0.0/24 is subnetted, 1 subnets

D       2.2.2.0 [90/409600] via 192.168.1.2, 00:03:23, Ethernet0/0

C    192.168.1.0/24 is directly connected, Ethernet0/0

r1#

------------------------------------------------------------------------------------

------------------------------------------------------------------------------------

R2:

查看邻居表：

r2#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq Type

                                            (sec)         (ms)       Cnt Num

0   192.168.1.1             Et0/0             12 00:01:17   20   200  0  8  

r2#

查看路由表：

r2#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

Gateway of last resort is not set

     1.0.0.0/24 is subnetted, 1 subnets

D       1.1.1.0 [90/409600] via 192.168.1.1, 00:01:41, Ethernet0/0

     2.0.0.0/24 is subnetted, 1 subnets

C       2.2.2.0 is directly connected, Loopback0

C    192.168.1.0/24 is directly connected, Ethernet0/0

r2#

总结（认证过程）：

只发送最小的一个KEY-D的密钥匙.并携带KEY=ID.当本路由器接受到对方发过来的KEY-ID和密钥时.先匹配收到的密钥的KEY-ID号与自己的KEY-ID号是否相同.如果KEY-ID号有相同的,则看密码是否相同,密码相同则认证通过.密码不同人证不通过.如果对方发过来的KEY-ID号自己没有相同的KEY-ID号,就向下一个匹配一个KEY-ID号中的密钥(既比收到的KEY-ID号大的的下一个KEY-ID),而且只向下匹配一次KEY-ID号中的密钥.既密文认证是先匹配KEY-ID在匹配KEY-ID的内容.